Ordinarily, two different types of drill bits are utilized in hand held drills and in stationary drill presses. In a hand held drill, the user is primarily interested in the cutting speed. Accordingly, the drill bit is designed to cut rapidly through the workpiece. In order to do this, the drill bit has very aggressive cutting angles. Thus, the relief angles, helical angles and cutting angles are designed to rapidly cut through a workpiece. Also, hand held drill users generally apply relatively constant, small forces to the drill during operation. High speed steel generally can be utilized as the material for the drill bit.
In a stationary drill press, life of the drill bit generally is most important to the user. Speed is generally a secondary consideration. In stationary drill presses, a variable force that is larger than that used in a hand-held drill is applied to the drill bit. Thus, as the drill bit dulls, an increased force is applied to maintain the same feed rate. Stationary drill presses are concerned with drilling a large number of holes in a reasonable time. Thus, a drill bit for a stationary drill press has less aggressive cutting angles and a larger chisel edge. This provides for additional stability during use of the drill bit. Also, the drill bits are designed to dissipate and minimize heat that occurs at the working tip during use.
A drill bit designed for a hand held drill is not stable enough, when utilized in a stationary drill press, so that failure occurs after a small number of holes are formed in a workpiece. Additionally, the drill bit is incapable of dissipating large amounts of heat that occurs at the working tip when it is utilized in a stationary drill press. Accordingly, hand held drill bits fail relatively quickly in a stationary drill press.
Drill bits designed for stationary drill presses do not cut fast enough to be used in a hand held drill. Also, due to their ability to dissipate heat, the material used for their manufacturing is brittle. Accordingly, lateral loads applied to these drill bits cause failure. Thus, since the design factors for drill bits used in stationary drill presses is diametrically opposite to drill bits used in hand held drills, the technologies have not been combined to provide a drill bit that functions satisfactorily in both hand held drilling applications as well as in stationary drill press applications.